碳纤维增强环氧复合材料吸湿行为研究

研究碳纤维增强环氧复合材料湿热环境下的吸湿行为。通过试验测试复合材料在温度T=71℃,相对湿度RH=85%环境下吸湿性能,获取吸湿曲线。结果表明复合材料吸湿初始阶段吸湿率和t1/2是呈线性增加的关系,吸湿扩散系数D为3.13×10-3mm2/h,吸湿一定时间后吸湿速率逐渐减小,吸湿1008h左右后,达到吸湿平衡,平衡吸湿率Mm为0.86%左右。结合吸湿Fick定律,建立反映此复合材料吸湿行为的吸湿模型,能较准确的预测此复合材料在该湿热环境下任意时刻的吸湿量及预估达到特定吸湿量所需的时间。     

循环湿热环境中CCF300/5405复合材料的吸湿脱湿行为

研究了CCF300碳纤维/5405双马树脂复合材料在71 ℃恒温水浸循环吸湿-脱湿行为。试样经过三次饱和吸湿-脱湿过程, 探讨不同循环次数CCF300/5405复合材料的吸湿率和水分扩散速率变化, 并采用SEM观察纤维/基体界面变化, 分析了造成循环湿热环境下复合材料体系吸湿-脱湿变化的原因。研究结果表明: CCF300/5405复合材料的吸湿行为基本满足Fick第二定律, 并且在水浸14天后达到饱和吸湿状态, 饱和吸湿率约为0.66%; 材料吸湿处理后, 纤维与基体间的界面遭到水分破坏, 产生大量空隙和裂纹, 使水分的扩散速率明显增加, 饱和吸湿率略有增大, 并且这种破坏不可逆。      

预固化环氧树脂基复合材料吸湿特性研究

研究了预固化碳纤维增强环氧树脂基复合材料的吸湿特性.采用水浸法对比研究了预固化复合材料与标准工艺固化复合材料的吸湿性能,实验先后在60℃和90℃水温下进行,利用真空烘箱在100℃对比研究了两种复合材料的脱湿性能.结果表明:预固化复合材料的吸湿率及吸湿速率均高于标准工艺固化复合材料;提高吸湿温度,两者的吸湿率都会继续增加,预固化复合材料的吸湿率提高幅度较大;预固化复合材料中的水分子不会被完全脱除.     

金荞麦多糖的吸湿保湿性能研究

通过干燥器控制湿度的方法,对金荞麦多糖进行吸湿和保湿性能研究。结果显示:64h时金荞麦多糖在RH为43%和81%条件下的吸湿率分别为46.26%和70.57%,在硅胶环境中的保湿率为4.88%;表明金荞麦多糖具有一定的吸湿和保湿性能,是一种具有一定开发潜力的天然保湿剂。     

丙烯酸-甲基丙烯酸共聚物的合成和吸湿性能

采用甲基丙烯酸(MAA)、丙烯酸(AA)为聚合单体,以亚硫酸氢钠-过硫酸铵为引发剂,采用水溶液聚合法制备了聚丙烯酸-甲基丙烯酸P(AA-MAA).系统地研究了单体浓度、单体配比、反应温度等各项聚合条件对聚合物吸湿性能的影响.在T=20℃、RH=90%条件下,与传统的硅胶、分子筛等吸湿材料的吸湿性能进行了对比.结果表明,硅胶和分子筛在10h内已经逼近吸湿平衡点,而P(AA-MAA)的吸湿率明显＞80%且仍未达到其最大吸湿容量.在吸湿性能测试的各个阶段,P(AA-MAA)的吸湿率是它们的5倍以上,明显优于传统的硅胶和分子筛.红外光谱分析证实了P(AA-MAA)共聚物的生成.     

浅谈术语“气体吸湿剂＂

“固体吸湿剂”、“液体吸湿剂”常作为吸湿剂中的两大类型被提及。固体吸湿剂利用吸附原理,对湿空气进行除湿;液体吸湿剂利用吸收原理,使空气达到除湿的效果。而压缩空气作为一种极为干燥的空气,我们称之为“气体吸湿剂”,此空气通过和湿空气混合,实现对湿空气稀释除湿的目的。同时经过压缩空气气体吸湿剂除湿后的空气可以与蒸发冷却技术相结合应用于空调中,大大提高蒸发冷却降温的效率。另外,在我国西北等干燥地区大气中存在着一种经过大自然除湿后的天然干燥空气一千空气,我们可充分利用这种气体吸湿剂,直接送入建筑物内消除室内的湿负荷,大大降低人工制冷除湿的能耗,同时充分利用“干空气能”,达到尽量采用蒸发冷却天然冷源降温的效果,从而实现建筑低能耗的目的。“气体吸湿剂”是一种新的吸湿剂概念,为此,本文对术语“气体吸湿剂”进行了初步的探讨。     

有机高分子吸湿材料的吸附模型与机理

选聚丙烯酸钠(PAA)、聚丙烯酰胺(PAM)、丙烯酸-甲基丙烯酸共聚物P(AA-MA)、丙烯酸-丙烯酰胺共聚物P(AA-AM)、丙烯酸-甲基丙烯酸-丙烯酰胺共聚物P(AA-AM-MA),系统研究其吸湿过程和机理。吸湿性能的测试结果表明,硅胶和分子筛10 h内便饱和,有机高分子吸湿材料仍能持久吸湿,其饱和吸湿容量比硅胶提高至少6%以上,比分子筛提高至少50%以上,吸湿速率快于硅胶和分子筛。吸附动力学实验表明,有机高分子吸湿材料的吸湿主要遵循准二级动力学模型,吸湿率受湿度和高分子树脂自身的吸附性能影响。Freundlich吸附等温模型证实有机高分子吸湿材料吸湿并非单层吸附,而是物理吸附和化学吸附同时发生,且多以化学吸附为主。热力学分析得该吸湿过程为吸热反应且可自发进行。     

湿热环境对复合材料正交板静拉伸性能的影响

对CCF300/BA9916复合材料正交板进行吸湿-脱湿实验,测定其在干态、湿态和脱湿条件下的静拉伸性能,研究了湿热环境下该材料的吸湿和脱湿行为。结果表明:在70℃水浸条件下CCF300/BA9916复合材料的吸湿过程与脱湿过程均符合Fick第二定律,试验件约在35 d后达到有效吸湿平衡状态,有效吸湿平衡率为0.85%;吸湿导致复合材料试验件的静拉伸性能下降了10.3%,而脱湿处理可使静拉伸性能得到一定程度的恢复。     

耐磨胶粘涂层的动态吸湿过程研究

依据矩形试件吸湿过程的实测数据描绘出涂层材料的吸湿浓度与吸湿应变曲线, 同时利用F ick 扩散定律的有关吸湿结论进行数据处理得到了扩散系数近似值。以此为基础, 进一步分析了实用涂层的吸湿浓度变化规律及吸湿引起的内应力。结果表明, 涂层平衡吸湿浓度4% 左右, 而相对材料初始强度, 吸湿引起的内应力很小      

吸湿后碳纤维复合材料正交层板拉伸疲劳性能

湿环境下复合材料疲劳性能会严重退化,影响结构的使用安全,在确定复合材料结构寿命时须考虑湿环境的影响.对常温下湿态和干态下碳纤维复合材料正交层合板的拉伸疲劳性能进行实验,研究饱和吸湿对正交层合板拉伸疲劳性能的影响,获得了两种环境下层合板的S-N曲线.在此基础上,建立有限元模型,并对吸湿后正交层合板的疲劳寿命和损伤演化情况进行预测,计算结果与实验结构吻合较好,证明了模型的有效性.结果表明,饱和吸湿对正交层合板的拉伸疲劳性能影响很大.吸湿后正交层合板的拉伸疲劳寿命明显低于干态情况,而且S-N曲线的斜率稍低,层合板的纤维损伤起始与扩展情况与干态情况也有较大差别.     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.     

Early ironwork in Biscay: Survey,excavation, experimentation and materials characterization. An integral study of the mountainside ironworks (ferrerías de monte or “haizeolak”)

ABSTRACT

The production of iron in Biscay (Basque Country, Spain) has been a hallmark of this territory of the North of the Iberian Peninsula throughout its history. The Archaeology team of the Basque Country Mining Museum has spent 13 years, so far, studying the origins of this activity through the evidences left at the old pre-hydraulic iron production workshops known as mountainside ironworks (ferrerías de monte) or haizeolak. It has catalogued 170 archaeometallurgical sites of this type in Biscay, and the archeological excavation of some of them has led to the knowledge of the different stages of the production process that took place in these workshops. The team has also experimentally reproduced the work carried out in a mountainside ironworks from the High Middle Ages, and it has currently started the characterization process of this type of activity through the study of the collected materials.     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.